perf/x86/intel/uncore: Expose an Uncore unit to IIO PMON mapping

perf/x86/intel/uncore: Expose an Uncore unit to IIO PMON mapping

Current version supports a server line starting Intel® Xeon® Processor
Scalable Family and introduces mapping for IIO Uncore units only.
Other units can be added on demand.

IIO stack to PMON mapping is exposed through:
    /sys/devices/uncore_iio_<pmu_idx>/dieX
    where dieX is file which holds "Segment:Root Bus" for PCIe root port,
    which can be monitored by that IIO PMON block.

Details are explained in Documentation/ABI/testing/sysfs-devices-mapping

Reported-by: kbuild test robot <[email protected]>
Signed-off-by: Alexander Antonov <[email protected]>
Signed-off-by: Roman Sudarikov <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Reviewed-by: Kan Liang <[email protected]>
Reviewed-by: Alexander Shishkin <[email protected]>
Link: https://lkml.kernel.org/r/[email protected]